qf_defer.cpp

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//============================================================================
// QP/C++ Real-Time Event Framework (RTEF)
//
// Copyright (C) 2005 Quantum Leaps, LLC. All rights reserved.
//
//                    Q u a n t u m  L e a P s
//                    ------------------------
//                    Modern Embedded Software
//
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-QL-commercial
//
// This software is dual-licensed under the terms of the open-source GNU
// General Public License (GPL) or under the terms of one of the closed-
// source Quantum Leaps commercial licenses.
//
// Redistributions in source code must retain this top-level comment block.
// Plagiarizing this software to sidestep the license obligations is illegal.
//
// NOTE:
// The GPL does NOT permit the incorporation of this code into proprietary
// programs. Please contact Quantum Leaps for commercial licensing options,
// which expressly supersede the GPL and are designed explicitly for
// closed-source distribution.
//
// Quantum Leaps contact information:
// <www.state-machine.com/licensing>
// <info@state-machine.com>
//============================================================================
#define QP_IMPL             // this is QP implementation
#include "qp_port.hpp"      // QP port
#include "qp_pkg.hpp"       // QP package-scope interface
#include "qsafe.h"          // QP Functional Safety (FuSa) Subsystem
#ifdef Q_SPY                // QS software tracing enabled?
    #include "qs_port.hpp"  // QS port
    #include "qs_pkg.hpp"   // QS facilities for pre-defined trace records
#else
    #include "qs_dummy.hpp" // disable the QS software tracing
#endif // Q_SPY
 
// unnamed namespace for local definitions with internal linkage
namespace {
Q_DEFINE_THIS_MODULE("qf_defer")
} // unnamed namespace
 
namespace QP {
 
//............................................................................
bool QActive::defer(
    QEQueue * const eq,
    QEvt const * const e) const noexcept
{
    // post with margin==0U to use all available entries in the queue
    bool const status = eq->post(e, 0U, m_prio);
 
    QS_CRIT_STAT
    QS_CRIT_ENTRY();
    if (status) { // deferring successful?
        QS_BEGIN_PRE(QS_QF_ACTIVE_DEFER, m_prio)
            QS_TIME_PRE();      // time stamp
            QS_OBJ_PRE(this);   // this active object
            QS_OBJ_PRE(eq);     // the deferred queue
            QS_SIG_PRE(e->sig); // the signal of the event
            QS_2U8_PRE(e->poolNum_, e->refCtr_);
        QS_END_PRE()
    }
    else { // deferring failed
        QS_BEGIN_PRE(QS_QF_ACTIVE_DEFER_ATTEMPT, m_prio)
            QS_TIME_PRE();      // time stamp
            QS_OBJ_PRE(this);   // this active object
            QS_OBJ_PRE(eq);     // the deferred queue
            QS_SIG_PRE(e->sig); // the signal of the event
            QS_2U8_PRE(e->poolNum_, e->refCtr_);
        QS_END_PRE()
    }
    QS_CRIT_EXIT();
 
    return status;
}
 
//............................................................................
bool QActive::recall(QEQueue * const eq) noexcept {
    QEvt const * const e = eq->get(m_prio); // get evt from deferred queue
 
    bool recalled = false;
    if (e != nullptr) { // event available?
 
        // post it to the front of the AO's queue.
        // NOTE: asserts internally if the posting fails.
        postLIFO(e);
 
        QF_CRIT_STAT
        QF_CRIT_ENTRY();
 
        if (e->poolNum_ != 0U) { // mutable event?
 
            // after posting to the AO's queue, the event must be referenced
            // at least twice: once in the deferred event queue (eq->get()
            // did NOT decrement the reference counter) and once in the
            // AO's event queue.
            Q_ASSERT_INCRIT(210, e->refCtr_ >= 2U);
 
            // decrement the reference counter once, to account for removing
            // the event from the deferred queue.
            QEvt_refCtr_dec_(e); // decrement the reference counter
        }
 
        QS_BEGIN_PRE(QS_QF_ACTIVE_RECALL, m_prio)
            QS_TIME_PRE();      // time stamp
            QS_OBJ_PRE(this);   // this active object
            QS_OBJ_PRE(eq);     // the deferred queue
            QS_SIG_PRE(e->sig); // the signal of the event
            QS_2U8_PRE(e->poolNum_, e->refCtr_);
        QS_END_PRE()
 
        QF_CRIT_EXIT();
 
        recalled = true; // success
    }
    else {
        QS_CRIT_STAT
        QS_CRIT_ENTRY();
 
        QS_BEGIN_PRE(QS_QF_ACTIVE_RECALL_ATTEMPT, m_prio)
            QS_TIME_PRE();      // time stamp
            QS_OBJ_PRE(this);   // this active object
            QS_OBJ_PRE(eq);     // the deferred queue
        QS_END_PRE()
 
        QS_CRIT_EXIT();
    }
    return recalled;
}
 
//............................................................................
std::uint16_t QActive::flushDeferred(
    QEQueue * const eq,
    std::uint_fast16_t const num) const noexcept
{
    std::uint16_t n = 0U; // the flushed event counter
    while (n < num) { // below the requested number?
        QEvt const * const e = eq->get(m_prio);
        if (e != nullptr) { // event obtained from the queue?
            ++n; // count one more flushed event
#if (QF_MAX_EPOOL > 0U)
            QF::gc(e); // garbage collect
#endif
        }
        else { // queue ran out of events
            break; // done flushing
        }
    }
 
    return n;
}
 
} // namespace QP